Re: [PATCH] af_packet: Don't use skb after dev_queue_xmit()

From: Michael Breuer
Date: Sun Jan 17 2010 - 17:35:26 EST

On 1/17/2010 5:17 PM, Jarek Poplawski wrote:
On Sun, Jan 17, 2010 at 11:26:46AM -0500, Michael Breuer wrote:
On 01/13/2010 04:16 PM, Michael Breuer wrote:
On 1/13/2010 4:09 PM, Jarek Poplawski wrote:
On Wed, Jan 13, 2010 at 03:39:37PM -0500, Michael Breuer wrote:

Update: after leaving the system up for a few days, I hit the DMAR
error again.
My proposal is to send some summary as a new thread, with dmar in the
subject, and cc-ed dmar maintainers.

Not sure I agree. The symptoms are identical to those I hit without DMAR earlier on. Also, as this issue only happens when there is high receive load, I'm thinking there's some sort of race between TX and RX within the sky2 driver, or hardware. I think that DMAR is correctly catching the error.
This happened during a scheduled backup from my win7
box. A reboot was required to re-enable eth0. After the error, eth0
was receiving, but was unable to transmit. For example, the log
reported arp bogons; DHCPINFORM/ACK sequences (where the ACK that
was logged was not transmitted), etc. The log was filled with sky2
eth0: tx timeout messages; as well as disable/enable of eth0.

I attempted to get things up again without a reboot, but failed.
Even rmmod& insmod did not fix whatever was broken on the TX side.

Note that this is similar to the earlier sky2 errors I had under
load with the variety of patches, and with or without DMAR enabled.
Just took way longer this time. Note that eth1 remained functional.

Unfortunately, with the latest set of patches installed, this is no
longer reproducible at will. I'd guess therefore that the patches
narrowed some hole, but didn't close it.
It would be nice to name those patches each time. Anyway, try this
again without DMAR.

Jarek P.

My bad: was running with the af_packet.c version 3 patch; and Stephen's v4 patch from last week. Both on 2.6.32 from git (so Can't move back to head as I've hit two unrelated issues.

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